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I'm a fan of cost-benefit analysis. The approach provides a systematic way to think through the consequences of public policies and provides a reasonable approach to debate merits and demerits of a policy.

Cost-benefit analysis shouldn't be the final word on a policy because there are some "rules" we may care about regardless of immediate short-run consequences. For example, even if a cost-benefit analysis found that the benefits to TV thieves outweighed the costs to prior TV owners, few would support a policy of decriminalizing TV theft, in part because a society that had such little respect for property rights is not likely one that would be prosperous in the long-run (or enjoyable to live in for that matter). All this is a way of saying that our moral intuitions often conflict (sometimes rightfully so) with a short-term utilitarian premise implied by cost benefit analysis (the trolley problem is a common example).

In the realm of food and public health policy, sometimes the way benefits and costs are calculated are myopic, fail to account for dynamic market responses to policies, and rest on shaky methodological assumptions. Moreover, when we find that benefits exceed costs, one should also ask: what is preventing the market from capitalizing on this arbitrage opportunity? Stated differently, there would need to be solid evidence of market failure (or some government failure) in addition to a positive cost-benefit test to justify a public policy.

Despite these qualms, I see cost-benefit analysis as a useful tool, and it provides one input into the decision making process.

Lately, I've been thinking about what happens to a cost-benefit analysis when one considers multiple policies - in an environment where are increasing calls for new regulations?

Suppose one did a cost-benefit analysis (CBA) on mandatory country of labeling for meat. Then, a CBA on a ban on use of subtherapeurtic antibiotics in meat production. Then, a CBA on a ban on growth hormones. Then, a CBA on banning gestation crates in pork production. Then, a CBA on banning transfats. Then, a CBA on new water regulations for confined animal feeding operations. Then, a CBA on a carbon tax on methane production from cows. (I could go on - these represent but a few of the policies that are commonly batted around that have some impact on meat and livestock markets.)

Is it possible that each of these policies - in isolation - could pass a cost benefit test, and yet when considered jointly fail the test? Stated differently, is it possible to strictly follow a cost-benefit rule when adopting public policies (only passing policies that pass a CBA) and wind up with a world that we find as less desirable than the one we started with?

I think the answer may be "yes." For example, each CBA in isolation will assume that the status quo prevails with regard to every other policy. But, the general equilibrium effects could differ from these individual partial-equilibrium analyses, particularly if there are nonlinearities.

Tyler Cowen recently linked to a new paper by Ian Martin and Robert Pindyck on policies related to catastrophic events that also seems relevant to this discussion.

How should we evaluate public policies or projects to avert or reduce the likelihood of a catastrophic event? Examples might include a greenhouse gas abatement policy to avert a climate change catastrophe, investments in vaccine technologies that would help respond to a “mega-virus,” or the construction of levees to avert major flooding. A policy to avert a particular catastrophe considered in isolation might be evaluated in a cost-benefit framework. But because society faces multiple potential catastrophes, simple cost-benefit analysis breaks down: Even if the benefit of averting each one exceeds the cost, we should not avert all of them.

Cowen summarized the paper as follows:

The main point is simply that the shadow price of all these small anti-catastrophe investments goes up, the more of them we do, and thus we cannot do them all, even if every single investment appears to make sense on its own terms.

Typical CBAs often ignore the the hundreds (if not thousands) of laws that already affect farmers' and food purveyors' ability to operate. It does make one wonder whether diminishing returns shouldn't feature more prominently in CBA.